Issue Description
Q:What's the meaning of statistics on packets at Ethernet port of NE40NE80?
Handling Process
Meanings of statistcis in Input:
1. shorts: packet with correct checksum and with a length less than 64-byte
2. jumbos: packet with correct checksum and with a length less than 1519-9018
3. giants: packet with extra length and correct checksum
4. pauses: packet being delayed
5. unicasts: unicast packet
6. multicasts: multicast packet
7. broadcasts: broadcast packet (including the packets with broadcast address as destination and those broadcasted)
8. fragments: packet with false checksum but with a length less than 64-byte
9. jabbers: packet with false checksum and extra length
10. crc: non-extra-long packet with false checksum
11. errors: packet with false L2 header
12. overruns: packets that cannot enter queue because it is full
Meaning of statistics in output:
1. Shorts, jambos, giants, unicasts, multicasts, broadcasts, jabbers, crc has been explained in input.
2. deferrals: packets that cannot be transmitted because of timeout
3. underruns: packets that cannot be transmitted because the speed of PMM is lower than that of the medium
4. aborts: packets that fail to be transmitted because of PMM
5. collisions: conflicted packets
6. lates: conflicted packets occured after transmitting 64-byte
7. singles: a single conflicted packet before transmitting 64-byte
8. multiples: multiple conflicted packets before transmitting 64-byte
9. excessives: packets that have been stopped transmitting because of multiple times confliction
